1. Field of the Invention
The present invention relates to turbocharged engines and related hardware. More particularly, the present invention relates to a clamping bracket for use in mounting a wastegate actuator to a turbocharger, and to a method of using the bracket. Even more particularly, the present invention relates to a mounting method and to a clamping bracket for mounting a wastegate actuator to a turbocharger assembly which provides improved adjustability in positioning the wastegate actuator on the turbocharger.
2. Description of the Background Art
Turbochargers, powered by high pressure exhaust gases produced by internal combustion engines, are widely used in automotive vehicles to supply pressurized intake air to the vehicle's combustion chamber, to yield increased engine power. A typical turbocharger normally includes a turbine housing and a compressor housing constructed side by side. The turbine housing contains an exhaust gas-driven turbine wheel mounted on a rotatable shaft, and the compressor housing contains a compressor wheel mounted on the other end of the same rotatable shaft, for concurrent rotation with the turbine wheel.
Turbochargers are also typically equipped with a wastegate, disposed in a passageway between the exhaust gas inlet and outlet portions of the turbine housing, to allow the flow of exhaust gas to bypass the turbine wheel as needed. The wastegate is opened, for example, when the intake manifold pressure exceeds a preset value, sometimes referred as a lift off pressure.
The wastegate includes four components, namely, an inlet portion, an outlet portion, a wastegate actuator and a wastegate valve.
The wastegate actuator generally includes a spring loaded diaphragm, housed within an actuator canister, and an actuator rod for actuating the spring loaded diaphragm. The wastegate actuator is mounted on the compressor housing of the turbocharger. The actuator canister is connected to the compressor portion of the turbocharger, through a sensing hose, to provide air pressure to the diaphragm. The diaphragm, which is controlled by intake manifold pressure, acts on the actuator rod for activating the wastegate valve which is mounted on the turbine housing of the turbocharger.
A wastegate valve is disposed in a passageway between the inlet portion and the outlet portion of the wastegate. The wastegate valve is normally closed in a default position, and held closed by the diaphragm spring housed inside the actuator canister. When the air pressure level of the intake manifold exceeds the preset value, the wastegate valve progressively opens the passageway, allowing some exhaust gas to bypass the turbine wheel of the turbocharger.
The diaphragm spring is selected or the length of the actuator rod is adjusted such that the wastegate valve remains in closed position up to a preset air pressure, and when the air pressure of the intake manifold exceeds the preset level, the actuator rod moves against the action of spring and opens the wastegate valve.
There has been an ongoing trend in engine compartment design, in recent years, to pack components tightly together under the hood. It will be appreciated that the different engine compartments, of different automotive vehicles, have different amounts of space available for mounting a turbocharger. Therefore, it is important to accommodate the turbocharger within the available space, oriented in a position to achieve effective performance of the turbocharger, and to achieve higher efficiency of the automotive engine.
In previous designs of mounting brackets for wastegate actuator, the wastegate actuator is mounted using a fixed bolt pattern, generally formed on the compressor housing, which severely limits the indexing possibilities of the wastegate actuator. See, e.g., FIGS. 5 and 6.
There are a few clamping and mounting devices used in automotive vehicles as illustrated in the U.S. Pat. Nos. 2,937,893 (Hill et al), 4,558,891 (Wagner et al), 4,059,045 (McClain), 5,199,260 (Iwick), 6,402,119 (Miska), and 6,658,846 (McEwan).
Hill et al., U.S. Pat. No. 2,937,893, issued in 1960 and entitled “Resealable Conduit Coupling with Abutting Resilient Flange Surfaces”, discloses a band-type conduit coupling for connecting two pipe sections together. The conduit coupling includes a band which wraps around the pipes to be joined, and the band is tightened by spinning a nut on a threaded shaft provided at one end of the band.
Wagner et al., U.S. Pat. No. 4,558,891, issued in 1985 and entitled “Clamp for Exhaust System”, discloses a band clamp for securing overlapping telescoped adjacent tubes in an exhaust system of automotive vehicle to form a substantially leak-proof joint. The band clamp includes a circular band and a bolt having a curved end secured thereto over a predetermined circumferential distance adjacent one end of the band and a straight threaded end extending through an extension secured adjacent to the opposite end of the band. A nut is provided on the straight threaded end of the bolt for tightening against the extension to draw the ends of the band together in near abutting relationship to engage the lap joint over a substantially continuous circumferential area. The extension either can bridge the gap to serve as a guide for the outer end of the band, or it can be an integral portion of the band.
McClain, U.S. Pat. No. 4,059,045, issued in 1977 and entitled “Engine Exhaust Rain Cap with Extruded Bearing Support Means”, discloses a circular metal band for mounting a rain cap mechanism to a circular exhaust pipe of a heavy duty vehicle.
Miska, U.S. Pat. No. 6,402,119, issued in 2002 and entitled “Textile-Reinforced Rubber Exhaust System Hanger”, discloses a hanging bracket assembly, for a muffler system of an automotive vehicle, which includes a plurality of the brackets on the vehicle frame that serve as mounting points for mounting for an exhaust pipe which has a plurality of circular clamps attached thereto at points corresponding to the brackets. Each clamp has a clamp pin integrally attached thereon that protrudes in the same direction as the pin of its corresponding bracket.
Iwick, U.S. Pat. No. 5,199,260, issued in 1993 and entitled “Wastegate Actuator Valve for a Turbocharger”, discloses a wastegate control valve for a turbocharger. McEwan, U.S. Pat. No. 6,658,846, issued in 2003 and entitled “Turbocharger With Wastegate”, discloses a turbocharger having an actuating rod which controls the wastegate. The disclosures of these U.S. Pat. Nos. 5,199,260 and 6,658,846, do not specifically discuss how the wastegate actuator is attached to the turbocharger, however, it appears that the wastegate actuator is attached to the turbocharger via bolts, which are positioned in a preset fixed bolt pattern on the turbocharger, which do not permit positioning of wastegate actuator on the turbocharger as desired.
However, none of the existing clamping devices or brackets are suitable for mounting the wastegate actuator on the turbocharger, in a manner that would permit a large range of positions at which the wastegate actuator could be mounted on the turbocharger. Increased turbocharger efficiency and increased engine power can be derived by properly positioning the wastegate actuator on the compressor housing of the turbocharger.
Therefore, a need exists in the art for an improved mounting bracket for orienting a wastegate actuator on a turbocharger body. More particularly, there is a need for a wastegate actuator mounting bracket which permits a large number of positioning possibilities to overcome the limitations encountered with the known art.